[v4,14/23] trace-cmd: Convert tsc timestamps to nanosecods when reading trace data from a file

Commit Message

Tzvetomir Stoyanov (VMware) March 25, 2021, 6:40 a.m. UTC

If there is information for TSC to nanoseconds conversion in the trace
file metadata, use it to recalculate the timestamps of all events.

Signed-off-by: Tzvetomir Stoyanov (VMware) <[e-mail]>
---
 lib/trace-cmd/trace-input.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

Patch

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index e1842cce..266b0b0c 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -1196,6 +1196,23 @@  static void free_next(struct tracecmd_input *handle, int cpu)
 	tracecmd_free_record(record);
 }
 
+/* This functions was taken from the Linux kernel */
+static unsigned long long mul_u64_u32_shr(unsigned long long a,
+					  unsigned long long mul, unsigned int shift)
+{
+	unsigned int ah, al;
+	unsigned long long ret;
+
+	al = a;
+	ah = a >> 32;
+
+	ret = (al * mul) >> shift;
+	if (ah)
+		ret += (ah * mul) << (32 - shift);
+
+	return ret;
+}
+
 static inline unsigned long long
 timestamp_correction_calc(unsigned long long ts, unsigned int flags,
 			  struct ts_offset_sample *min,
@@ -1283,6 +1300,10 @@  static unsigned long long timestamp_calc(unsigned long long ts,
 
 	if (handle->ts2secs)
 		ts *= handle->ts2secs;
+	else if (handle->tsc_calc.mult) {
+		ts -= handle->tsc_calc.offset;
+		ts = mul_u64_u32_shr(ts, handle->tsc_calc.mult, handle->tsc_calc.shift);
+	}
 
 	return ts;
 }